Photosensitive Epilepsy
may be a familiar term to people acquainted with playing video games. A
mandatory warning appears in the beginning of video or computer games and even
a few animated programs such as cartoons for kids, which have flashing graphics
or flickering lights.Dr. Prithika Chary, a neurologist
and neurosurgeon practicing at Kauvery Hospital, Chennai, Tamil Nadu speaks
to Medindia about Photosensitive Epilepsy.

Flickering Sunlight

Moving Vehicle

Sunlight Flickering Through Leaves

Dr. Prithika Chary Neurologist Neurosurgeon

Flashing Light

Eye Patch

Q. What triggers photosensitive epilepsy?

A.Photosensitive Epilepsy is caused by natural lights such as sun
flickering through the leaves or when a person is moving while in a vehicle
watching irregular patterns of light. Artificial lights also cause photosensitive
epilepsy when a person looks down from escalators, exposed to disco
lights, or sees certain patterns such as stripes or checks.

Q. How does photosensitive epilepsy differ from other
seizures?

A.
There are many kinds of seizures. Grand mal seizure, generalized tonic clonic
seizure affecting the brain, and absence seizures where a person is
momentarily absent. It is often associated with eye blinks and staring. A
person could get several attacks of absence seizures. Another kind is the focal
seizure where the arm or face twitches, involuntary repetitive
movements (automatism) and chewing or champing movements are observed. Then
there is complex partial seizure where a person's awareness or the
ability to respond fails.

Photosensitive Epilepsy is
a generalized tonic clonic seizure.

Q. People of all ages watch TV or play video games so how is
it only a few people have photosensitive epilepsy?

A.Three
out of hundred people with epilepsy have photosensitive epilepsy. It
depends on where the problem is, which is usually in the occipital lobe (the
part of the brain responsible for vision). All people with epilepsy exposed to
prolonged hours of viewing computer or television sometimes without even moving
their eyes face the chances of developing photosensitive epilepsy.

Q. What is
the diagnosis of photosensitive epilepsy?

A.
Even routine electroencephalogram (EEG) may not detect photosensitive epilepsy.
It is provoked during the EEG sessions where hyperventilation is induced in a
person with epilepsy. Certain fits come about during these sessions even in the
EEG rooms. In addition to EEGs, Photic stimulation aids in diagnosis,
meaning a person with epilepsy is exposed to a certain number of flashes
beginning from 5 flashes, then 10 flashes up to 40 flashes. If the
person does have photosensitive epilepsy, the seizures will confirm the
diagnosis.

Q. How can
people affected by photosensitive epilepsy stay protected?

A.
Young people below the age of 20 run a risk if they visit discos or dance clubs
because of the flickering lights. People with photosensitive epilepsy should
avoid viewing red flashing graphics. If the flashes per second (refresh rate)
on the screen is anywhere between 15 to 20 hertz, it could trigger
photosensitive epilepsy. So when the refresh rate (flashes per second) of
a screen is low it causes seizures in people with photosensitive epilepsy. But
these days, advanced model of screens have a refresh rate of 100 hertz, which
does not pose a threat to people with photosensitive epilepsy. But an outdated
screen, which has a low refresh rate of 50 hertz or below, may cause seizures
in a person with photosensitive epilepsy.

Q.What are some of the precautionary measures for a person with
photosensitive epilepsy?

A.
A person with photosensitive epilepsy must avoid looking at the reflection of
sunlight on water no matter how alluring it is. As a first aid measure,
when there is a chance of seizure, the hand should immediately cover one eye or
the person can wear an eye patch. This act reduces the number of
neurons being stimulated, thus reducing the risk.

Q. When is
it an emergency for a person to seek medical assistance? Who should one contact
in case of an emergency?

A.
A person with epilepsy can get seizures anytime. But it does not mean they are
always vulnerable to having seizures. Sometimes the condition of epilepsy is
complacent and a person may not have any seizure. The specialist one should
visit to get medical attention is a neurologist.

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